In copending applications Ser. No. 08/228,213, now U.S. Pat. No. 5,590,649, and continuation-in-part applications Ser. Nos. 08/561,923 and 08/556,547, both applications pending, (Flehr Hohbach Test Albritton & Herbert files A-59155-1 and A-59155-2, respectively), and Flehr Hohbach Test Albritton & Herbert file No. 08/561 928, which was submitted to the U.S. Patent Office for filing on Nov. 22, 1995, there is described an apparatus for measuring a perturbation induced in the body to determine physiological parameters. The apparatus disclosed in said applications includes an exciter positioned over a blood vessel of the patient for inducing a transmitted exciter waveform into the patient. A non-invasive sensor is spaced from the exciter over the blood vessel. The non-invasive sensor is configured to sense a hemo-parameter and to generate a non-invasive sensor signal representative of the hemo-parameter containing a component of a physiological parameter waveform and a component of a received exciter waveform. In this context, a hemo-parameter is defined as any physiological parameter related to vessel blood such as pressure, flow, volume, velocity, blood vessel wall motion, blood vessel wall position and other related parameters. A processor determines the relationship between a property of the received exciter waveform and a property of the physiological parameter to provide the physiological parameter. In one embodiment, the physiological parameter measured is blood pressure. Exciters, sensors and processors can also be used to analyze and track other physiological parameters such as vascular wall compliance, strength of ventricular contractions, vascular resistance, fluid volume, cardiac output, myocardial contractility and other related parameters. It will be apparent that use of the present exciter-detector unit is not limited to use in the foregoing apparatus.